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| United States Patent |
5,165,611
|
|
Ragnarsson
|
November 24, 1992
|
Wood size reduction apparatus
Abstract
A comminutor for reducing large diameter wood products and stumps to size,
comprised of a reduction chamber, with an impact rotor positioned
concentrically therein, in combination with a housing, drive motor and
infeed chute. The impact rotor is formed with a plurality of horizontally
elongated impact hammers at its periphery. The impact hammers are arranged
in sets of impact hammer rows oriented at an angle to the rotational axis
of the impact rotor. Each set of impact hammers has one row of hammers
having radial angles increasing along the rotor's longitudinal axis in the
axial direction of the rotor and a second opposing row of hammers having
radial angles decreasing along the rotor's longitudinal axis in the axial
direction of the rotor. The rotor is positioned so that the elongated wood
product or stump falling under the influence of gravity through the infeed
chute is directed against the impact hammers, and repelled ahead of the
rotor's rotational direction against an anvil formed along one side of the
reduction chamber.
| Inventors:
|
Ragnarsson; Anders T. (66 Pelham Rd., Salem, NH 03079)
|
| Appl. No.:
|
635880 |
| Filed:
|
December 28, 1990 |
| Current U.S. Class: |
241/88.4; 241/189.1; 241/191 |
| Intern'l Class: |
B02C 013/06; B02C 013/28 |
| Field of Search: |
241/88.4,189 R,197,191,195,189 A
|
References Cited
U.S. Patent Documents
| 646249 | Mar., 1900 | Williams | 241/197.
|
| 764268 | Jul., 1904 | Boileau | 241/91.
|
| 2045691 | Jun., 1936 | Armstrong | 241/189.
|
| 3224688 | Dec., 1965 | Beiter | 241/189.
|
| 4151959 | May., 1979 | Deister | 241/69.
|
| 4177954 | Dec., 1979 | Ostreng | 241/167.
|
| 4226375 | Oct., 1980 | Cameron | 241/88.
|
| 4919344 | Apr., 1990 | McKie | 241/32.
|
Primary Examiner: Rosenbaum; Mark
Assistant Examiner: Husar; John M.
Attorney, Agent or Firm: Davis, Bujold & Streck
Claims
I claim:
1. An apparatus for comminuting wood by shearing comprising:
a) a housing having a comminution cavity disposed therein;
b) an impact rotor mounted for rotation within said housing about an axis
of rotation;
c) a drive means for rotating said rotor;
d) an infeed means to said cavity;
e) a plurality of comminuting blades mounted on said rotor disposed to form
oppositely oriented helical blade arrays each coaxial with said axis of
rotation; and
f) an egress means for exiting comminuted particles from said cavity.
2. An apparatus according to claim 1 wherein a drive motor is operatively
connected to rotate said rotor.
3. An apparatus according to claim 1 wherein each said blade defines an
impact face aligned with the helical angle of the helical array with which
it is associated whereby the impact faces of all blades of each array
together form a substantially continuous helical impact face coaxial with
said axis of rotation.
4. An apparatus according to claim 3 wherein the oppositely oriented
helical arrays are mirror images of one another.
5. An apparatus according to claim 3 further comprising an anvil positioned
within said cavity to cooperate with said blades in said comminution.
6. An apparatus according to claim 3 further comprising a grate assembly
positioned so that comminuted wood product is forced onto the grate
assembly and the rotation of the rotor grinds and shears said product so
as to force said product through said grate assembly.
7. An apparatus according to claim 1 wherein said infeed means extends for
substantially the entire axial length of said rotor and is positioned to
allow the influence gravity to cause a wood product to be directed against
said blades.
8. An apparatus according to claim 1 wherein there are at least four
separate said helical arrays disposed evenly about said rotor.
9. An apparatus according to claim 8 wherein said helical arrays do not
circumferentially overlap and each extend substantially the entire axial
length of said rotor.
10. An apparatus according to claim 1 wherein there are at least four
separate said helical arrays of alternating opposite orientations.
11. An apparatus according to claim 1 further comprising a wedge shaped
means positioned within said cavity to impede wood from being repelled by
said rotor out through said infeed means.
12. An apparatus according to claim 1 wherein the arrays are separate from
one another.
13. An apparatus according to claim 1 wherein each helical blade array has
only a single helical orientation and is circumferentially spaced from
each next adjacent helical blade array.
14. An apparatus according to claim 13 wherein each helical blade array has
an opposite helical orientation to each next adjacent helical blade array.
15. An apparatus for comminuting wood by shearing comprising a housing,
having a comminution cavity disposed therein;
an impact rotor mounted for rotation within said housing about an axis of
rotation;
an infeed means connected to said cavity and extending substantially the
entire length of said rotor;
a plurality of impact blades mounted on said rotor and disposed to form a
plurality of oppositely oriented circumferentially spaced separate helical
arrays of said blades coaxial with said axis of rotation, said blades each
having a cutting surface oriented in the direction of rotation of said
rotor; and
wherein said cavity has anvil means positioned to cause wood being
comminuted to be sheared by rotation of said blades.
16. An apparatus according to claim 15 wherein said anvil means includes a
removable grate assembly positioned adjacent said blades to shear said
wood being comminuted and to allow adjacent said blades to shear said wood
being comminuted and to allow wood chips from said cavity and a means to
impede material being comminuted from being ejected through the infeed
means.
17. An apparatus according to claim 15 wherein each helical blade array has
only a single helical orientation and is circumferentially spaced from
each next adjacent helical blade array.
18. An apparatus according to claim 17 wherein each helical blade array has
an opposite helical orientation to each next adjacent helical blade array.
Description
BACKGROUND OF THE INVENTION
This invention relates to comminutors, and more particularly to an impact
rotor assembly for reducing large diameter wood products and stumps to
size.
Impact crushers for the reduction and classification of ore utilizing an
impact rotor to obtain the initial reduction of large ore chunks are known
in the prior art. See U.S. Pat. No. 3,887,141 to P. M. Francis. Francis
discloses a mill in a single housing. A primary reduction chamber located
within the housing is fed raw ore with variable particle sizes up to and
including chunks on the order of 1 foot in diameter. An impact rotor is
positioned within the primary reduction chamber and secured to the output
shaft of a drive motor. The impact rotor mounts a plurality of elongated
hammer bars around its periphery. These hammer bars are oriented parallel
to the rotational axis of the impact rotor. The rotor is positioned so
that the ore, falling under the influence of gravity, is directed against
the hammer bars and repelled therefrom with great force against the sides
of the primary reduction chamber.
Application of Francis-type pulverizing mills to wood waste is also known.
See U.S. Pat. No. 4,151,959 to C. L. Deister. The Deister patent discloses
an impact pulverizer having a rotor located concentrically within a
reduction chamber. The rotor has a plurality of generally
radially-extending impact blades. The radial angle of the blades increases
along the axis of the rotor to provide each of the blades with a slope in
the axial direction of the rotor. The spiral rotational action of the
pieces as they are propelled and ricocheted around the primary reduction
chamber achieves a faster pulverizing action than Francis-type pulverizing
mills. The spiral rotational action also requires less power that the
Francis mill.
Prior art pulverizing mills are ineffective in reducing logs because the
wood is not hard enough to shatter, i.e., the resiliency of wood requires
a shearing and grinding effect. Although neither the Francis nor the
Deister mills are able to reduce wood logs to size, the principal of the
spiral Deister rotor has been applied to a rotary wood hog for reducing
logs. Rawlings Construction Co. of Montana, markets a rotary wood hog
which uses a helical rotor to reduce elongated wood products to size. By
use of an anvil at the front of the rotary hog, the Rawlings helical rotor
is able to shear and grind pieces of the log during each revolution of the
rotor.
The increasing radial angle of the Rawlings rotor blades attempts to move
the material being acted upon in a generally spiral rotational motion.
Because logs are generally most efficiently fed into a rotary wood hog at
lengths of ten feet or more and in a direction where a log's longitudinal
axis is parallel to the rotor's radial axis, the spiraling action of the
rotor blades will move the end of the log being acted upon by the rotor
toward one corner the reduction chamber. The log being reduced will
thereby tend to change from an upright vertical position to a horizontal
position frequently causing a bridging-type jam when the length of the log
matches the width of the rotor housing, i.e., the log will bridge the
rotor and block additional material from reaching the rotor blades. This
is especially a problem when dealing with larger diameter wood products,
i.e., 24 inches to 40 inches because of the extensive shut down required
to remove the jammed pieces which are large and heavy. Even without
jamming, uneven wear of the rotor blades will take place.
SUMMARY OF THE INVENTION
In view of the foregoing disadvantages inherent in the known types of
devices now present in the prior art, the present invention provides a
shredder/crusher for reducing larger diameter wood products to size. As
such, the general purpose of the present invention, which will be
described subsequently in greater detail, is to provide a shredder/crusher
which will not jam when comminuting wood products.
To attain this, the present invention comprises in combination with a
housing and a drive motor, a reduction chamber disposed within the
housing. An infeed chute is connected to the chamber and is adapted to
feed larger diameter wood products and stumps to the interior thereof.
An impact rotor is positioned concentrically within the reduction chamber
and operatively connected to the drive motor. The impact rotor is formed
with a plurality of horizontally elongated impact hammers at its
periphery. The impact hammers are arranged in sets of impact hammer rows
oriented at an angle to the rotational axis of the impact rotor. Each set
of impact hammers has one row of hammers having radial angles increasing
along the rotor's longitudinal axis in the axial direction of the rotor
and a second opposing row of hammers having radial angles decreasing along
the rotor's longitudinal axis in the axial direction of the rotor. The
rotor is positioned so that the elongated wood product to stump falling
under the influence of gravity through the infeed chute is directed
against the impact hammers, and repelled ahead of the rotor's rotational
direction against an anvil forced along one side of the reduction chamber.
The impact hammer arrangement provides shearing of that portion of the
wood product engaged by the rows of hammers. The action of each set of
opposing rows of impact hammers on the wood product keeps the wood product
generally horizontally and vertically positioned at its point of entry
thereby avoiding bridge jamming and uneven wear on the impact hammers. The
reduced wood product is forced onto a grating positioned about the bottom
of the chamber. The continuous rotation of the impact rotor will grind and
press sheared pieces of wood product through the grate openings to a
desired size.
According to the invention there is provided an apparatus for comminuting
wood by shearing comprising a housing having a comminution cavity disposed
therein; an rotor mounted for rotation within said housing about an axis
of rotation; a drive means for rotating said rotor; an infeed means to
said cavity; a plurality of comminuting blades mounted on said rotor
disposed to form oppositely oriented helical blade arrays each coaxial
with said axis of rotation; and an egress means for exiting comminuted
particles from said cavity.
Also according to the invention there is provided an apparatus for
comminuting wood shearing comprising a housing, having a comminution
cavity disposed therein; an rotor mounted for rotation within said housing
about an axis of rotation; an infeed means connected to said cavity and
extending substantially the entire length of said rotor; a plurality of
blades mounted on said rotor and disposed to form a plurality of
oppositely oriented circumferentially spaced separate helical arrays of
said blades coaxial with said axis of rotation, said blades each having a
cutting surface oriented in the direction of rotation of said rotor; and
wherein said cavity has an anvil means positioned to cause wood being
comminuted to be sheared by rotation of said blades.
The instant invention overcomes Rawlings' tendency to jam when reducing
larger diameter wood products, while still taking advantage of Deister's
shearing effect. The instant invention's arrangement of impact hammers or
blades in sets with opposing helical rows results in the log tending to
stay in that same position relative to the rotor as when it first entered
the reduction chamber against the anvil while the impact hammers or blades
shear the wood.
This together with other objects of the invention, along with various
features of novelty which characterize the invention, are pointed out with
particularity in the claims annexed hereto and forming a part of this
disclosure. For a better understanding of the invention, its operating
advantages and the specific objects attained by its uses, reference should
be had to the accompanying drawings and descriptive matter in which there
is illustrated a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side plan view of one embodiment of a shredder/crusher
according to the present invention.
FIG. 2 is a side sectional view of the shredder/crusher.
FIG. 3 is a flattened diagrammatic view of the impact rotor of the present
invention.
FIG. 4A is a side elevational view of the first rotor segment in FIG. 2.
FIG. 4B is a side elevational view of the middle rotor segment in FIG. 2.
FIG. 4C is a side elevational view of the last rotor segment in FIG. 2.
FIG. 5 is a side sectional view of another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings in detail wherein like elements are indicated by
like numerals, there is shown an embodiment of the invention 1 comprising
a shredder/crusher with a rotary assembly for reducing large diameter wood
products and stumps to size. The present invention has a housing 10 with a
top 11, bottom 12, front 13, back 14 and two sides 15, and a drive motor
5. A reduction chamber 25 is centrally disposed within the housing 10. A
downwardly sloping infeed chute 20 is joined to the reduction chamber 25
and is adapted to feed large diameter wood logs, stumps and other wood
products such as telephone poles, pilings, railroad ties, beams and posts,
to the interior of the reduction chamber 25. Mounted interiorly of the
reduction chamber 25 is an impact rotor 50. The rotor 50 is carried on a
shaft 85 which extends transversely across the reduction chamber 25,
penetrates the housing sides 15 and is seated on bearings (not shown)
bolted to support plates 86 bolted to the outside of the housing sides 15.
One protruding end 87 of the shaft 85 is operatively connected to the
drive motor 5 which provides rotational power to the shaft 85.
The impact rotor 50 is comprised of a plurality of axially contiguous,
disk-like segments 51. When installed on the shaft 85 expandable lock
rings (not shown) bind the rotor outside segments 52, 54 to the shaft 85.
The body 60 of each segment 51 has a generally quadrilateral shape and is
welded to each adjacent segment 51. The side faces 61 of the segments 51
are ground absolutely flat and the resulting friction between the side
faces 61 of adjacent segments 51 will help keep the rotor segments 51
turning together without slippage and also provides for perfect alignment
of each segment's central radial shaft opening 55. Each segment 51 is as
wide as possible. In this embodiment, a 60 inch rotor length embodiment is
illustrated containing five axial segments 51, each of which is 12 inches
wide. In this embodiment of the invention each axial segment 51 has a main
body 60 and four generally radially extending impact hammers 62 about its
periphery 57. The impact hammers 62 also form a seat portion 64 for a
striker plate 110. Each impact hammer 62 has two threaded holes 63 for
bolting a striker plate 110 with two corresponding holes 113 to the front
face 65 of the hammer 62. The front face 65 of a hammer 62 is defined as
that side facing in the counterclockwise direction of impact rotor 50
rotation as shown in FIGS. 1-5. Each striker plate 110 is attached to a
hammer front face 65 by means of a bolt 114 inserted through each striker
plate hole 113 into a corresponding impact hammer hole 63. The bolt holes
113 and 63 are positioned as low as possible on the hammer 62, i.e., close
to the axial segment main body 60. The bolts 114 are threaded and are held
in place by cooperation of their threads with the hammer hole 63 threads.
Alternatively, each bolt 114 could be held in place by means of a nut 115
on the back side 66 of the hammer 62.
The axial segments 51 are so arranged about the shaft 85 that the impact
hammers 62 are formed into sets 67 of impact hammer rows 68, 69 and
oriented at an angle to the counter-clockwise rotational axis of the
impact rotor 50. Each set 67 of impact hammers 62 has one longitudinal row
68 of impact hammers 62 having radial angles increasing along the rotor's
longitudinal axis in the axial direction of the rotor 50 and a second
opposing row 69 of impact hammers 62 having radial angles decreasing along
the rotor's longitudinal axis in the axial direction of the rotor 50. The
radial angle of increase and decrease which provides the best shearing is
15 degrees. As rotor length increases, the radial angle may decrease to
approximately 10 degrees. The maximum radial angle range appears to be 5
degrees to 25 degrees.
This arrangement of sets 67 and rows 68, 69 is illustrated diagrammatically
in FIG. 3. To better understand the rotor segment configuration, FIGS.
4A-4C illustrate the two end segments 52 and 54 as well as the middle
segment 53 of the present five segment embodiment and should be examined
in conjunction with FIG. 3. The second and fourth segments are not shown.
The first segment 52 is the segment 51 fully visible in FIG. 2.
The rotor 50 is centrally positioned within the reduction chamber 25 so
that the elongated wood product or stump falling under the influence of
gravity through the infeed chute 20 is directed against the striker plates
110 attached to the impact hammers 62, and repelled ahead of the rotor's
rotational direction against an anvil 70 formed along the upper front
portion 33 of the reduction chamber 25. The anvil 70 has a wear plate 78
attached to its rearward face 77. The impact hammer arrangement of the
present invention shears that portion of the wood product engaged by the
impact hammer striker plates 110 and the anvil bottom 71. In the present
invention's nominal 60 inch rotor, the impact rotor 50 rotates at a rate
of 400 revolutions per minute. This provides 1600 hammer row hits on the
wood product per minute. The effect of this is that the action of the
opposing rows 68, 69 of impact hammers 62 in each set 67 on the wood
product keeps the wood product generally positioned vertically and
horizontally at the same relative point where it initially entered thereby
avoiding jamming and uneven wear on the impact hammers striker plates 110.
The reduction chamber 25 has an upper portion 30 and a lower portion 40.
The rotor shaft 85 is horizontally and centrally positioned between the
upper and lower portions 30, 40 transversely extending across the
reduction chamber 25. The upper reduction chamber portion 30 has a
quadrilateral polygonal shape and has a top 31, bottom 32, front 33, back
34, and two sides 35. The upper portion top 31 opens and is connected to
the bottom 21 of the infeed chute. The striker plate top 111 to opposing
striker top 111 segment diameter of the impact rotor 50 is slightly less
than the front 33 to back 34 length of the reduction chamber upper portion
30. As stated above the upper portion has an anvil 70 formed along the
upper front portion 33 of the reduction chamber 25. The anvil 70 acts as a
counter-weight and shearing surface aid for the rotor 50. Because wood is
so resilient, the anvil 70 must be an absolutely solid surface. In this
embodiment the anvil 70 is made of steel and is 12 inches thick and
approximately 60 inches wide. A one inch thick wear plate 78 is attached
to the rear surface of the anvil 70. The direction of rotation of the
impact rotor 50 is counterclockwise towards the anvil 70. Wood product is
thrown against the anvil wear plate 78 by the striker plates 110. The
anvil-backed wear plate 78 then momentarily holds the wood product in
place while the impact hammer-backed striker plates 110 shear portions of
the wood product as the striker plates 110 by the bottom 71 of the anvil
70 and wear plate 78. The anvil bottom 71 has a small vertical flange 72
on each side 73. The flanges 72 protrude through the housing front 13 and
are connected to the housing front 13 by means of shear bolts 74. The
advantage of this arrangement over prior art devices is that the sheared
bolt 74 can be easily removed. Prior art devices usually have the shear
bolts threaded into the side 73 of the anvil plate 70.
Across the reduction chamber upper portion back wall 34 a wedge shaped
piece 38 having a quadrilateral cross section is attached. The purpose of
the wedge 38 is to keep logs from hitting the impact hammers rows 68, 69
on the vertical upward portion of their rotation cycle and being thrown
back out of the infeed chute 20. The quadrilateral shape eliminates a
"shelf" for material to land upon.
The reduction chamber lower portion 40 also has a generally quadrilateral
polygonal shape and has a top 41, bottom 42, front 43, back 44, and two
sides 45. The lower portion top 41 opens up to and forms the upper portion
bottom 32. A curved grate assembly 90 comprised of a frame 98 and grate
insert 99 is positioned along the lower periphery 57 of the impact rotor
50 for passing comminuted material of a desired size. The grate 90 is
connected at one end 91 at the approximate juncture of the upper and lower
portion front walls 33, 43 just below the anvil 70, and at its other end
92 at the approximate juncture of the upper and lower portion back walls
34, 44. As the wood product is sheared, the reduced wood product is pushed
onto the grate 90. The rotating impact rotor 50 will press the reduced
wood product through the grate 90. The residue of reduced wood product
which does not pass through the grate 90 is returned by the impact rows
68, 69 to the reduction chamber upper portion 30. The residual wood
product is thrown against the wedge's lower side 39 and then again against
the anvil 70 and wear plate 78 for further reduction. The grate 90 is
connected at its rear end 92 by means of a removable hinge bolt 93. The
grate front end 91 is connected by means of two removable shear bolts 94.
In case of a serious jam the shear bolts 94 will break thereby releasing
the grate 90 and preventing damage to the grate and impact rotor 50. The
bolts 93 and 94 are removable to permit removal of the grate insert 90 and
reinstallation in the reverse direction. Since the grate insert holes (not
shown) wear in a front to rear direction, reversal avoids the necessity of
immediate replacement of the entire grate 90 because of wear. Grates 90
under this arrangement will last twice as long.
Although the present invention is designed primarily for use with larger
diameter wood products, it may also be used for other typical pulverizable
materials. When pulverizable materials such as concrete with reinforced
bars are to be reduced, the present invention may have two options added.
As may be seen in FIG. 5 a blade spring 75 is attached horizontally across
the anvil's forward face 76 and attached to the housing front 13. The
anvil's rearward face 77 has the wear plate 78 against which the
pulverizable material is hammered. Use of the blade spring 75 will allow
the anvil 70 to flex during comminution of particularly hard materials and
thereby decrease the potential for jamming. The invention's grate 90 is
also changed, especially when reducing concrete with reinforcing bars
which do not lend themselves to reduction and must be removed from the
pulverizer. The concrete and bars are substantially separated by the
hammering action as described above. If the same grating was used as with
wood product reduction, the bars would almost immediately jam up the
grating insert 99. The wood reduction grate assembly 90 is therefore
replaced with a partial grate assembly 95 positioned to the front 43 of
the reduction chamber lower portion 40. The grate insert openings 96 (not
shown) are elongated with a longitudinal axis in the direction or rotation
of the impact rotor. A spring system 100 is installed between the grate
assembly 95 and front wall 43. The spring system 100 is joined to the
partial grate assembly under surface 97 and provides flexing as the
reinforcing bars pass through, thereby substantially reducing the
potential for jamming.
In the embodiments described above the axial segments 51 have a preferably
solid main body 60 made of solid steel construction. Conventional air
intake means are used within the reduction chamber.
It is understood that the above-described embodiments are merely
illustrative of the application. Other embodiments may be readily devised
by those skilled in the art which will embody the principles of the
invention and fall within the spirit and scope thereof.
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